Crucible shuttle assembly and method of operation

Abstract

A crucible handling shuttle includes a pair of opposed dual crucible-gripping arms mounted on a rotatable head and moves between an induction furnace pedestal and a crucible loading station, such that one pair of arms pick up a crucible loaded with a preweighed sample, the shuttle moves to the induction furnace, where the other pair of arms grip and remove a spent crucible. The shutter head then rotates to deposit the new sample-holding crucible onto the pedestal and subsequently moves out of the furnace area to a sample disposal chute positioned between the crucible loading station and the furnace, whereupon the spent crucible is dropped for disposal. The shuttle head is then rotated and moved to the loading station to pick up a new crucible.

1. A shuttle system for loading and unloading crucibles to and from a furnace associated with an analyzer and a crucible loading station comprising:
 a shuttle including pairs of opposed crucible-gripping arms for simultaneously gripping crucibles on opposite sides of an axis of rotation and further including actuators for selectively opening at least one arm of said pairs of gripping arms to grip and release crucibles; 
 a rotating head supporting said pairs of arms; 
 a linear drive coupled to said shuttle for moving said rotating head and said gripping arms between a crucible-holding pedestal of a furnace and a loading station for providing sample-holding crucibles for introduction into the furnace; and 
 a mechanism for selectively raising and lowering said pairs of gripping arms, wherein said mechanism comprises a fixed base plate, a housing for said shuttle, and a pivot connection between said housing and base. 
 
     
     
       2. The system as defined in  claim 1  and further including a linear actuator coupled between said base and housing for pivoting said housing to raise and lower said pairs of arms. 
     
     
       3. The system as defined in  claim 2  wherein said gripping arms are held in a crucible-gripping position by a spring. 
     
     
       4. The system as defined in  claim 3  wherein said rotating head is mounted to a carriage and said linear drive comprises a drive screw threadably coupled to said carriage. 
     
     
       5. The system as defined in  claim 4  wherein said gripping arms include curved ends for partially circumscribing a cylindrical crucible. 
     
     
       6. A gripping assembly for holding and releasing crucibles comprising:
 a first pair of crucible-gripping arms pivotally mounted on a rotary head; 
 a second pair of gripping arms mounted on said head in opposed relationship to said first pair of gripping arms; 
 springs for holding said first pair of arms and said second pair of arms in a crucible-holding position; 
 a tapered actuator movably coupled between said first and second pairs of arms for selectively opening said gripping arms to release and hold a crucible; and 
 wherein said rotary head includes a pair of cylinders for receiving actuating pistons, an actuating piston positioned in each of said cylinders and having a conical tip which extends above said rotary head when actuated, and wherein said pistons are positioned in said head such that said conical tip extends between said pair of arms to open said arms when said pistons are actuated. 
 
     
     
       7. The gripping assembly as defined in  claim 6  wherein said pistons are pneumatically actuated and include a return spring coupled between said pistons and said head for retracting said conical tip from between said pair of arms to allow said arms to close for gripping a crucible. 
     
     
       8. A shuttle assembly for loading and unloading ceramic crucibles between a crucible loading station and a pedestal of an induction furnace associated with an analyzer comprising:
 a shuttle including a pair of opposed crucible-gripping arms for simultaneously gripping two crucibles on opposite sides of an axis of rotation; 
 said shuttle including a head for rotatably supporting said arms; 
 a linear drive coupled to said shuttle for moving said head and gripping arms between a crucible-holding pedestal of said furnace and a loading station providing sample-holding crucibles for introduction into the furnace, wherein said linear drive also moves said shuttle to a discharge chute for dispensing spent crucibles; 
 wherein said shuttle includes a carriage to which said head is mounted and said linear drive includes a drive screw coupled to said carriage for moving said carriage between a furnace and a crucible loading station; and 
 a fixed base plate and a housing for said carriage and drive screw, and a pivot connection between said housing and base plate at a location spaced from said shuttle for pivotally raising and lowering said shuttle to lift a crucible from and lower a crucible onto the pedestal. 
 
     
     
       9. The assembly as defined in  claim 8  and further including a linear actuator extending between said base plate and said housing for raising and lowering said shuttle. 
     
     
       10. A crucible loading/unloading shuttle assembly comprising;
 a shuttle including opposed spring-loaded crucible-gripping arms; 
 said shuttle including actuators for moving said arms between open and closed positions; 
 said shuttle assembly further including a housing and a linear drive positioned in said housing and coupled to said shuttle for moving said shuttle between a furnace and a crucible loading station; 
 said shuttle assembly further including a fixed base plate for positioning between a furnace and a crucible loading station wherein said housing is pivotally mounted to said base plate; and 
 a second linear actuator coupled between said housing and said base plate for raising and lowering said shuttle. 
 
     
     
       11. The assembly as defined in  claim 10  wherein said shuttle further includes a rotary head to which said gripping arms are coupled.